A terminal constant temperature and pressure hot and cold water control system and control method

Abstract

The present invention discloses a terminal constant temperature and constant pressure hot and cold water control system and control method, the system comprises a water supply pump group, a pressure sensor, a heat exchanger, a temperature sensor A, a temperature sensor B, a circulation pump group, a one-way valve and a controller, the water inlet of the water supply pump group is connected to the water supply pipe, the water outlet of the water supply pump group is connected to the cold water supply pipe and the heat exchanger water inlet pipe at the same time, the heat exchanger water inlet pipe is connected to the water inlet of the heat exchanger, the water outlet of the heat exchanger is connected to the hot water supply pipe, a hot water return pipe is connected to the end of the hot water supply pipe, the other end of the hot water return pipe is connected to the water inlet of the circulation pump group, and the water outlet of the circulation pump group is connected to the water inlet of the one-way valve. The present invention realizes constant pressure water supply at the water use end, makes the water pressure at the user end more stable, the pressure fluctuation is smaller, and can reduce energy loss; at the same time, it also realizes the precise start and stop of the circulation pump, avoids excessive circulation, reduces energy loss, and ensures the stability of water temperature at the water use end.

Description

Technical Field

[0001] The invention relates to a terminal constant-temperature and constant-pressure cold and hot water control system and a control method, belonging to the technical field of water supply control. Background Art

[0002] In high-end hotels, office buildings and other places, rooms are required to be supplied with hot and cold water, and there are high requirements for the stability of the water pressure and water temperature supplied to the user end to improve the user's water experience.

[0003] The prior art is to set a variable frequency constant pressure water supply pump group in the water supply area, set a pressure sensor at its outlet, and set two water supply pipes respectively, one of which directly supplies cold water to the water supply area, and the other pipe heats the supplied cold water through a heat exchanger to provide hot water to the water supply area. A return water pipe is led out at the end of the hot water supply pipe, and the return water pipe sends the water with too low water temperature in the hot water pipe back to the heat exchanger through a set of circulating pump groups for heating and then sends it to the water use end. Its control method is as follows: on the one hand, a pressure sensor set at the outlet of the variable frequency pump group provides a feedback signal to the controller, and the controller compares the signal with the set pressure, and performs PID operation on the difference, and drives the inverter with the operation result, and the inverter controls the speed of the pump group motor to realize the constant water pressure control of the pump group outlet; on the other hand, the return water temperature is detected by the temperature sensor installed at the water inlet of the circulating pump group, and the circulation pump is controlled by the return water temperature value. When the return water temperature value is lower than the set value, the circulation pump is started, and when the return water temperature value reaches the set temperature value, the circulation pump is stopped.

[0004] The above system has two disadvantages:

[0005] 1. Since the control of the water supply pump group uses the pump outlet pressure sensor signal as the measurement feedback value, and the pump outlet pressure value is used as the constant pressure target value, this constant pressure control method will cause large fluctuations in the end water pressure when the water consumption in the water supply area changes, and the unit water supply energy consumption is too large when the water consumption is small.

[0006] 2. Since the control of the circulating pump uses the temperature sensor installed at the water inlet of the circulating pump to compare the measured value with the set value to realize the start and stop control of the circulating pump, it will cause large fluctuations in the hot water temperature at the water end and frequent start and stop of the circulating pump, resulting in high energy consumption. Summary of the invention

[0007] In order to solve the above technical problems, the present invention provides a terminal constant temperature and constant pressure hot and cold water control system and control method to solve the problems of large fluctuations in water temperature and water pressure at the user end of the current hot and cold water supply system and high energy consumption.

[0008] The present invention is constructed as follows: a terminal constant temperature and constant pressure hot and cold water control system, comprising a water supply pump group, a pressure sensor A, a pressure sensor B, a heat exchanger, a temperature sensor A, a temperature sensor B, a circulation pump group, a one-way valve and a controller, wherein the water inlet of the water supply pump group is connected to the water supply pipe, the water outlet of the water supply pump group is connected to the cold water supply pipe and the heat exchanger water inlet pipe at the same time, a pressure sensor B is installed at the water outlet of the water supply pump group, the heat exchanger water inlet pipe is connected to the water inlet of the heat exchanger, the water outlet of the heat exchanger is connected to the hot water supply pipe, and the end of the hot water supply pipe is connected to A hot water return pipe, the other end of which is connected to the water inlet of the circulation pump group, the water outlet of the circulation pump group is connected to the water inlet of the one-way valve, and the water outlet of the one-way valve is connected to the water inlet pipe of the heat exchanger; a pressure sensor A is installed on the hot water return pipe near the water inlet of the circulation pump group, and a temperature sensor A and a temperature sensor B are installed in sequence at a certain distance on the hot water supply pipe near the water outlet end of the heat exchanger, and the water supply pump group, pressure sensor A, pressure sensor B, temperature sensor A, temperature sensor B and circulation pump group are electrically connected to the controller through cables respectively.

[0009] Furthermore, the heat exchanger is respectively connected with a heat medium water inlet pipe and a heat medium water return pipe, a heat medium electric regulating valve is installed on the heat medium water inlet pipe, and the heat medium electric regulating valve is electrically connected to the controller.

[0010] Furthermore, a cold water outlet valve is installed at the end of the cold water supply pipe, and a hot water outlet valve is installed at the end of the hot water supply pipe.

[0011] Furthermore, the water supply pump group is connected to the water supply pump group inverter through a cable, the circulating pump group is connected to the circulating pump group driver through a cable, and the water supply pump group inverter and the circulating pump group driver are electrically connected to the controller through cables respectively.

[0012] At the same time, the present invention also provides a control method based on the above-mentioned terminal constant temperature and constant pressure cold and hot water control system, including a constant pressure control method and a constant temperature control method:

[0013] The constant pressure control method is as follows: when the circulation pump group is not running, the controller collects the return water pressure value of the hot water return pipe through the pressure sensor A, and transmits the return water pressure value to the controller, the controller performs PID operation on the return water pressure value and the set pressure value to generate a pressure control value, and transmits the generated pressure control value to the water supply pump group inverter, the water supply pump group inverter controls the speed of the water supply pump group according to the pressure control value to realize the terminal constant pressure water supply function; when the circulation pump group is running, the controller collects the outlet pressure value of the water supply pump group through the pressure sensor B, and transmits the outlet pressure value to the controller, the controller performs PID operation on the outlet pressure value and the set pressure value to generate a pressure control value, and transmits the generated pressure control value to the water supply pump group inverter, the water supply pump group inverter controls the speed of the water supply pump group according to the pressure control value to realize the terminal constant pressure water supply function;

[0014] The constant temperature control method: the controller collects the temperature value in the hot water supply pipe through the temperature sensor A or the temperature sensor B, and transmits the temperature value to the controller, the controller performs PID operation on the collected temperature value and the set temperature value to obtain the temperature control value, and transmits the obtained temperature control value to the heat medium electric regulating valve, and controls the output water temperature of the heat exchanger by adjusting the opening value of the heat medium electric regulating valve to realize the terminal constant temperature water supply function.

[0015] In the above method, when the terminal water temperature changes, the constant temperature control method is:

[0016] Step 1: The controller collects the temperature value B in the hot water supply pipe through the temperature sensor B, and compares the temperature value B with the set temperature value. When the temperature value B is less than the set temperature value, the circulation pump group is started;

[0017] Step 2: The controller collects the temperature value A of the temperature sensor A. When the temperature value A reaches the set temperature value, the controller starts the timing program and starts timing;

[0018] Step 3: The controller again collects the temperature value B in the hot water supply pipe through the temperature sensor B. When the temperature value B also reaches the set temperature value, the timing time value recorded by the controller is TA;

[0019] Step 4: Assuming that the distance between temperature sensor A and temperature sensor B is L1, and the distance between the installation position of temperature sensor B and the end of the hot water supply pipe is L2, the hot water flow rate S in the pipe can be calculated as S = L1 / TA. Based on the hot water flow rate S, the running time TB=L2 / S of the circulation pump group can be calculated. At this time, the controller starts timing. When the running time of the circulation pump group reaches TB, the water temperature at the end reaches the set temperature value, and the circulation pump group stops running.

[0020] Due to the adoption of the above technical solution, the advantages of the present invention are:

[0021] 1. It realizes constant pressure water supply at the end of water use, making the water pressure at the user end more stable, with smaller pressure fluctuations, and reducing energy loss;

[0022] 2. The circulation pump can be started and stopped accurately to avoid over-circulation, reduce energy loss and ensure stable water temperature at the water end. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the connection structure of the present invention.

[0024] Explanation of the accompanying drawings: 1-water supply pipe, 2-water supply pump group, 3-pressure sensor A, 4-cold water supply pipe, 5-heat medium inlet pipe, 6-heat medium electric regulating valve, 7-heat medium return pipe, 8-heat exchanger, 9-heat exchanger inlet pipe, 10-hot water supply pipe, 11-temperature sensor A, 12-temperature sensor B, 13-cold water outlet valve, 14-hot water outlet valve, 15-hot water return pipe, 16-circulating pump group, 17-check valve, 18-controller, 19-water supply pump group inverter, 20-circulating pump group driver, 21-pressure sensor B. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0026] Example

[0027] like Figure 1 As shown, the terminal constant temperature and constant pressure hot and cold water control system of the present invention comprises a water supply pump group 2, a pressure sensor A3, a pressure sensor B21, a heat exchanger 8, a temperature sensor A11, a temperature sensor B12, a circulation pump group 16, a one-way valve 17 and a controller 18. The water inlet of the water supply pump group 2 is connected to the water supply pipe 1, and the water outlet of the water supply pump group 2 is connected to the cold water supply pipe 4 and the heat exchanger inlet pipe 9 at the same time. A pressure sensor B21 is installed at the water outlet of the water supply pump group 2, the heat exchanger inlet pipe 9 is connected to the water inlet of the heat exchanger 8, and the water outlet of the heat exchanger 8 is connected to the hot water supply pipe 10. The hot water return pipe 1 is connected to the end of the hot water supply pipe 10. 5. The other end of the hot water return pipe 15 is connected to the water inlet of the circulation pump group 16, the water outlet of the circulation pump group 16 is connected to the water inlet of the one-way valve 17, and the water outlet of the one-way valve 17 is connected to the heat exchanger water inlet pipe 9; a pressure sensor A3 is installed on the hot water return pipe 15 and close to the water inlet of the circulation pump group 16, and a temperature sensor A11 and a temperature sensor B12 are installed in sequence at a certain distance on the hot water supply pipe 10 and close to the water outlet end of the heat exchanger 8. The water supply pump group 2, the pressure sensor A3, the pressure sensor B21, the temperature sensor A11, the temperature sensor B12 and the circulation pump group 16 are electrically connected to the controller 18 through cables respectively.

[0028] The heat exchanger 8 is respectively connected to a heat medium water inlet pipe 5 and a heat medium water return pipe 7, and a heat medium electric regulating valve 6 is installed on the heat medium water inlet pipe 5, and the heat medium electric regulating valve 6 is electrically connected to the controller 18. In this example, the heat medium used by the heat exchanger 8 is hot water, and the speed at which the hot water enters the heat exchanger 8 can be controlled by adjusting the opening of the heat medium electric regulating valve 6.

[0029] A cold water outlet valve 13 is installed at the end of the cold water supply pipe 4 , and a hot water outlet valve 14 is installed at the end of the hot water supply pipe 10 .

[0030] In order to achieve unified control of the water supply pump group 2 and the circulation pump group 16, the water supply pump group 2 is connected to the water supply pump group inverter 19 through a cable, and the circulation pump group 16 is connected to the circulation pump group driver 20 through a cable. The water supply pump group inverter 19 and the circulation pump group driver 20 are electrically connected to the controller 18 through cables respectively.

[0031] At the same time, the present invention also provides a control method based on the above-mentioned terminal constant temperature and constant pressure cold and hot water control system, including a constant pressure control method and a constant temperature control method:

[0032] The constant pressure control method is as follows: when the circulation pump group 16 is not running, the controller 18 collects the return water pressure value of the hot water return pipe 15 through the pressure sensor A3, and transmits the return water pressure value to the controller 18, the controller 18 performs PID operation on the return water pressure value and the set pressure value to generate a pressure control value, and transmits the generated pressure control value to the water supply pump group inverter 19, the water supply pump group inverter 19 controls the speed of the water supply pump group 2 according to the pressure control value to realize the terminal constant pressure water supply function; when the circulation pump group 16 is running, the controller 18 collects the outlet pressure value of the water supply pump group 2 through the pressure sensor B21, and transmits the outlet pressure value to the controller 18, the controller 18 performs PID operation on the outlet pressure value and the set pressure value to generate a pressure control value, and transmits the generated pressure control value to the water supply pump group inverter 19, the water supply pump group inverter 19 controls the speed of the water supply pump group 2 according to the pressure control value to realize the terminal constant pressure water supply function;

[0033] When the hot water outlet valve 14 on the hot water supply pipe 10 is opened, that is, someone is using hot water, the constant temperature control method is as follows: the controller 18 collects the temperature value in the hot water supply pipe 10 through the temperature sensor A11 or the temperature sensor B12, and transmits the temperature value to the controller 18. The controller 18 performs PID operation on the collected temperature value and the set temperature value to obtain a temperature control value, and transmits the obtained temperature control value to the heat medium electric regulating valve 6. The output water temperature of the heat exchanger 8 is controlled by adjusting the opening value of the heat medium electric regulating valve 6 to realize the terminal constant temperature water supply function.

[0034] When the hot water outlet valve 14 on the hot water supply pipe 10 is closed, that is, when no one is using hot water, when the water temperature at the end changes, in order to ensure that the water temperature at the end of the hot water supply pipe 10 is the same as the set temperature, the constant temperature control method is:

[0035] Step 1, the controller 18 collects the temperature value B in the hot water supply pipe 10 through the temperature sensor B12, and compares the temperature value B with the set temperature value. When the temperature value B is less than the set temperature value, the circulation pump group 16 is started;

[0036] Step 2: The controller 18 collects the temperature value A of the temperature sensor A11. When the temperature value A reaches the set temperature value, the controller 18 starts the timing program and starts timing;

[0037] Step 3: The controller 18 again collects the temperature value B in the hot water supply pipe 10 through the temperature sensor B12. When the temperature value B also reaches the set temperature value, the timing time value recorded by the controller 18 is TA;

[0038] Step 4: Assuming that the distance between temperature sensor A11 and temperature sensor B12 is L1, and the distance between the installation position of temperature sensor B12 and the end of the hot water supply pipe 10 is L2, the hot water flow rate S in the pipe can be calculated as L1 / TA, and the running time TB=L2 / S of the circulation pump group 16 can be calculated based on the hot water flow rate S; at this time, the controller 18 starts timing, and when the running time of the circulation pump group 16 reaches TB, the water temperature at the end reaches the set temperature value, and the circulation pump group 16 stops running. It is worth noting that the existing hot water supply pipe 10 is coated with an insulation layer. Therefore, when the diameter and material of the hot water supply pipe 10 are the same, the heat dissipation, flow rate and other parameters of each section of the pipe are regarded as approximate invariants, and the running time TB=L2 / S of the circulation pump group 16 still holds.

[0039] In summary, the present invention installs two temperature sensors A11 and B12 at a distance of L1 on the hot water supply pipe 10, and obtains the time TA consumed by the hot water from the temperature sensor A11 to the temperature sensor B12 through the controller 18, so as to calculate the hot water flow rate S = L1 / TA, and then calculate the time TB=L2 / S when the hot water is transported from the position of the temperature sensor B12 to the end of the hot water supply pipe 10. In this way, the operating time TB of the circulation pump group 16 can be accurately obtained, so as to avoid frequent starting and stopping of the circulation pump group 16, reduce the energy consumption of the system, and ensure the stability of the water temperature at the water-using end.

Claims

1. A control method for a terminal constant temperature and constant pressure hot and cold water control system, the control system comprising a water supply pump group (2), a pressure sensor A (3), a pressure sensor B (21), a heat exchanger (8), a temperature sensor A (11), a temperature sensor B (12), a circulation pump group (16), a one-way valve (17) and a controller (18), characterized in that: The water inlet of the water supply pump group (2) is connected to the water supply pipe (1), and the water outlet of the water supply pump group (2) is connected to the cold water supply pipe (4) and the heat exchanger water inlet pipe (9) at the same time. A pressure sensor B (21) is installed at the water outlet of the water supply pump group (2). The heat exchanger water inlet pipe (9) is connected to the water inlet of the heat exchanger (8), and the water outlet of the heat exchanger (8) is connected to the hot water supply pipe (10). A hot water return pipe (15) is connected to the end of the hot water supply pipe (10). The other end of the hot water return pipe (15) is connected to the water inlet of the circulation pump group (16), and the water outlet of the circulation pump group (16) is connected to the one-way valve (17). The water inlet of the one-way valve (17) is connected to the water inlet pipe (9) of the heat exchanger; a pressure sensor A (3) is installed on the hot water return pipe (15) and close to the water inlet of the circulation pump group (16); a temperature sensor A (11) and a temperature sensor B (12) are installed in sequence at a certain distance on the hot water supply pipe (10) and close to the water outlet end of the heat exchanger (8); the water supply pump group (2), the pressure sensor A (3), the pressure sensor B (21), the temperature sensor A (11), the temperature sensor B (12) and the circulation pump group (16) are respectively electrically connected to the controller (18) through cables; The control method includes a constant pressure control method and a constant temperature control method: The constant pressure control method is as follows: when the circulation pump group (16) is not running, the controller (18) collects the return water pressure value of the hot water return pipe (15) through the pressure sensor A (3), and transmits the return water pressure value to the controller (18); the controller (18) performs PID operation on the return water pressure value and the set pressure value to generate a pressure control value, and transmits the generated pressure control value to the water supply pump group inverter (19); the water supply pump group inverter (19) controls the speed of the water supply pump group (2) according to the pressure control value, so as to realize the terminal constant pressure supply. water function; when the circulation pump group (16) is running, the controller (18) collects the outlet pressure value of the water supply pump group (2) through the pressure sensor B (21), and transmits the outlet pressure value to the controller (18); the controller (18) performs PID operation on the outlet pressure value and the set pressure value to generate a pressure control value, and transmits the generated pressure control value to the water supply pump group inverter (19); the water supply pump group inverter (19) controls the rotation speed of the water supply pump group (2) according to the pressure control value, so as to realize the terminal constant pressure water supply function; The constant temperature control method comprises: a controller (18) collects the temperature value in the hot water supply pipe (10) through a temperature sensor A (11) or a temperature sensor B (12), and transmits the temperature value to the controller (18); the controller (18) performs PID operation on the collected temperature value and the set temperature value to obtain a temperature control value, and transmits the obtained temperature control value to a heat medium electric regulating valve (6); and the output water temperature of the heat exchanger (8) is controlled by adjusting the opening value of the heat medium electric regulating valve (6), so as to realize a terminal constant temperature water supply function.

2. The control method of the terminal constant temperature and constant pressure hot and cold water control system according to claim 1, characterized in that: The heat exchanger (8) is respectively connected to a heat medium water inlet pipe (5) and a heat medium water return pipe (7), a heat medium electric regulating valve (6) is installed on the heat medium water inlet pipe (5), and the heat medium electric regulating valve (6) is electrically connected to a controller (18).

3. The control method of the terminal constant temperature and constant pressure hot and cold water control system according to claim 1, characterized in that: A cold water outlet valve (13) is installed at the end of the cold water supply pipe (4), and a hot water outlet valve (14) is installed at the end of the hot water supply pipe (10).

4. The control method of the terminal constant temperature and constant pressure hot and cold water control system according to claim 1, characterized in that: The water supply pump group (2) is connected to the water supply pump group frequency converter (19) via a cable, the circulation pump group (16) is connected to the circulation pump group driver (20) via a cable, and the water supply pump group frequency converter (19) and the circulation pump group driver (20) are respectively electrically connected to the controller (18) via cables.

5. The control method of the terminal constant temperature and constant pressure hot and cold water control system according to claim 1, characterized in that: When the end water temperature changes, the constant temperature control method is: Step 1, the controller (18) collects the temperature value B in the hot water supply pipe (10) through the temperature sensor B (12), and compares the temperature value B with the set temperature value. When the temperature value B is less than the set temperature value, the circulation pump group (16) is started to work; Step 2, the controller (18) collects the temperature value A of the temperature sensor A (11), and when the temperature value A reaches the set temperature value, the controller (18) starts the timing program and starts timing; Step 3, the controller (18) again collects the temperature value B in the hot water supply pipe (10) through the temperature sensor B (12). When the temperature value B also reaches the set temperature value, the timing time value recorded by the controller (18) is TA; Step 4: Assuming that the distance between the temperature sensor A (11) and the temperature sensor B (12) is L1, and the distance between the installation position of the temperature sensor B (12) and the end of the hot water supply pipe (10) is L2, the hot water flow rate S in the pipe can be calculated as S=L1 / TA, and the operating time TB=L2 / S of the circulation pump group (16) can be calculated based on the hot water flow rate S; at this time, the controller (18) starts timing, and when the operating time of the circulation pump group (16) reaches TB, the water temperature at the end reaches the set temperature value, and the circulation pump group (16) stops running.

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